Narrative:

Cleared by salt lake center for the GPS 30 into ggw via jitag. Cleared to cross jitag at 5;800 [feet]. I descended early and crossed the fix at 5;800 [feet]because earlier in the trip departing billings; we only picked up trace icing at that altitude. We flew the 11 miles to hukal picking up light to moderate ice; with the intensity growing. My plan was to blow the boots once we had collected enough ice to get a good break and hand fly the approach. There was no trim movement and our indicated airspeed was around 140 KIAS; plenty of speed in my opinion. We turned inbound at hukal and as the glideslope came alive; I went in range and lowered the gear preparing to disengage the autopilot and blow the boots. The pilot monitoring called airspeed. I noticed the airspeed decaying to about 110 [knots] followed by the yoke moving forward and aft in my hands as if the tail plane was starting to stall. I disconnected the autopilot and added power and leveled off; and with the added power; the aircraft started a shallow climb. We deviated high and to the left of course; but upon exiting the tail plane buffet; navigated back towards the localizer and glideslope while blowing the boots multiple times. The course was regained easily enough to continue the approach because I certainly did not want to stay in the icing environment. We broke out at about 1;000 AGL and came over the numbers at about 110 knots. I experienced another tail plane buffet through the yoke again during the flare; and landed without incident. I rolled out to the end and exited to the left on taxiway charlie. Starting our descent early to cross jitag at 5;800 [feet] put us in the clouds for 11 miles. We could have crossed hukal at 5;800 [feet] and still would have been okay for the approach. The airspeed decay could be attributed to the ice buildup since normal procedures for power settings were observed during the flight.also; the delay in blowing the boots may have attributed; but I make it a practice to try not to blow the boots prematurely. When the boots were blown; a sizable amount of ice was removed from the wing and tail. I would try to stay in VMC longer; even though we experienced trace icing earlier.

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Original NASA ASRS Text

Title: Air Taxi flight crew reported an early descent led to ice accumulation and possible tail stall.

Narrative: Cleared by Salt Lake Center for the GPS 30 into GGW via JITAG. Cleared to cross JITAG at 5;800 [feet]. I descended early and crossed the fix at 5;800 [feet]because earlier in the trip departing Billings; we only picked up trace icing at that altitude. We flew the 11 miles to HUKAL picking up light to moderate ice; with the intensity growing. My plan was to blow the boots once we had collected enough ice to get a good break and hand fly the approach. There was no trim movement and our indicated airspeed was around 140 KIAS; plenty of speed in my opinion. We turned inbound at HUKAL and as the glideslope came alive; I went in range and lowered the gear preparing to disengage the autopilot and blow the boots. The Pilot Monitoring called airspeed. I noticed the airspeed decaying to about 110 [knots] followed by the yoke moving forward and aft in my hands as if the tail plane was starting to stall. I disconnected the autopilot and added power and leveled off; and with the added power; the aircraft started a shallow climb. We deviated high and to the left of course; but upon exiting the tail plane buffet; navigated back towards the localizer and glideslope while blowing the boots multiple times. The course was regained easily enough to continue the approach because I certainly did not want to stay in the icing environment. We broke out at about 1;000 AGL and came over the numbers at about 110 knots. I experienced another tail plane buffet through the yoke again during the flare; and landed without incident. I rolled out to the end and exited to the left on Taxiway Charlie. Starting our descent early to cross JITAG at 5;800 [feet] put us in the clouds for 11 miles. We could have crossed HUKAL at 5;800 [feet] and still would have been okay for the approach. The airspeed decay could be attributed to the ice buildup since normal procedures for power settings were observed during the flight.Also; the delay in blowing the boots may have attributed; but I make it a practice to try not to blow the boots prematurely. When the boots were blown; a sizable amount of ice was removed from the wing and tail. I would try to stay in VMC longer; even though we experienced trace icing earlier.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.